1. Field of the Invention
Example embodiments of the present invention relate to a light-emitting assembly and an interactive display device having the light-emitting assembly. More particularly, example embodiments of the present invention relate to a light-emitting assembly capable of providing a touch screen panel that uses infrared lights and visible lights in a uniform manner, and an interactive display device having the light-emitting assembly.
2. Description of the Related Art
Touch panels are currently used in a wide variety of devices and allow a user to input information by simply touching an icon or area defined on the touch panel. For example, touch panels are now used in cell phones, Personal Digital Assistants (PDAs), computers, vending machines, various medical equipment, etc. Many business and government agencies also use kiosks system that include touch panels that the user can touch to input or request information. Navigation systems provided in vehicles or cell phones also use touch panels.
A panel that performs both a display function and a touch function is referred to herein as a touch screen panel. In a touch screen panel, a display function is used to display information on the panel, and a touch function is used to receive information from the user through application of pressure to the outside of the panel. The second substrate of the touch screen panel includes a photo sensor and a switching element controlling the photo sensor. When pressure is applied to the outside surface of the panel, the photo sensor absorbs an incident light having a specific wavelength to generate a photo current.
A central process unit (CPU) connected to the touch screen panel may calculate a touch position by using a difference between the photo current and a dark current generated by the photo sensor before the incident light is provided to the photo sensor. Upon being touched, the incident light absorbed into the photo sensor has a wavelength different from that of a visible light used for displaying the image in the touch screen panel. For example, the incident light absorbed into the photo sensor may be an infrared light.
Thus, a light-emitting assembly providing the touch screen panel with light may include both a first light source emitting infrared light and a second light source emitting visible light.
A direct-illumination type light-emitting assembly is used in order to uniformly receive the light from each of the first and second light sources, so as to provide the touch screen panel with the light in a uniform manner, and in order to improve luminance. For example, several of the first light sources are disposed on a surface facing the touch screen panel in a grid pattern, and each of the second light sources are disposed in a region divided by the four first light sources, so that the first and second light sources are uniformly disposed on the surface facing the touch screen panel. However, when the direct-illumination type light-emitting assembly is used, many light sources are needed so that the manufacturing cost and power consumption are both increased.
An edge-illumination type light-emitting assembly has also been employed as the light-emitting assembly and which does not have the drawbacks of the direct-illumination type light emitting assembly described above. In the edge-illumination type light-emitting assembly, first light sources emitting infrared light and second light sources emitting visible light are disposed at side portions of a light guide plate. However, in the edge-illumination type light-emitting assembly, the amount of receiving space for holding the first and second light sources may be limited. Moreover, it can be difficult to uniformly provide both the infrared lights and the visible lights to the touch screen panel.